The invention is in the field of circular lamp units, such as screw-in units having a circular fluorescent lamp and a ballast.
Various types of screw-in fluorescent lamp units have been devised, for taking the place of incandescent lamps in ceiling sockets and in table lamps and floor lamps, and are economical to operate and conserve electrical energy because they consume less than half the electrical energy consumed by incandescent lamps for the same brightness. U.S. Pat. No. 4,258,287 to Frederick Hetzel and U.S. Pat. No. 4,278,911 to Rudolph Metoff each discloses a screw-in central hub containing a ballast, and a replaceable circular lamp assembly positioned on the hub. The connector wires for the lamp are contained in a spoke that is an integral unit with the lamp bulb. U.S. Pat. No. 4,161,020 to Miller discloses a circular lamp unit having a rigid socket on the hub for connection to a circular lamp bulb, and U.S. Pat. No. 3,059,137 to Reaves discloses a circular lamp unit have a bundle of wires extending from a central ballast unit for connection to a circular lamp.